1. Out of the blue
To appear out of nowhere without any warning, to happen quite suddenly
Greg has decided to quit his job out of the blue, and go travelling for a year!
2. Blue pencil
To censor something, or limit the information that is shared
The reports about how soldiers were being treated abroad had been blue-penciled by the authorities.
3. A blue-eyed boy
A critical description of a boy or young man who is always picked for special favors by someone in a position of higher authority
He is such a blue-eyed boy! I don’t like that the manager always treats him as if he is special, it is not fair on the rest of us!
4. A bolt from the blue
When some unexpected bad news is received
It was a complete bolt from the blue for us, we had no idea that they were having problems, let alone getting divorced!
5. Blue blood
Used to describe someone from a noble and wealthy family
Many of the blue bloods in our town were invited to the royal wedding.
6. Blue ribbon
To be of superior quality or distinction, the best of a group
Blue ribbon panels of experts were invited to investigate the extraordinary remains.
7. Talk a blue streak
When someone talks very much and very rapidly
The woman in the hospital bed next to me talked a blue streak all day.
8. Feel blue
When someone looks or feels depressed or discontented
What’s that the matter with you today? You seem really blue. Is there something you’d like to talk about?
9. Blue in the face
To try really hard to win someone’s agreement, but usually end unsuccessfully
I kept trying to convince him that it was a good idea until I was blue in the face, but he’s so stubborn, he just kept disagreeing with me!
10. once in a blue moon
To occur extremely rarely, or only once in a lifetime
My sister is working in Africa, she hardly ever has the time to call us. My parents only hear from her once in a blue moon.